Grease an 8 by 8-inch pan with butter, or line it with waxed paper.,In a heavy-bottomed saucepan, combine the sugar, chocolate, 1 1/2 tablespoons of the butter, the half-and-half, and the corn syrup. Stir with a wooden spoon over medium heat until the sugar is dissolved and the chocolate is melted.,Increase the heat and bring to a boil without stirring. Reduce the heat to medium-low, cover, and cook for 3 minutes. Remove the cover and attach a candy thermometer to the pot. Cook until the thermometer reads 234°F.,______,Pour the fudge into the prepared pan. Let it sit in a cool dry area until firm, 3 to 4 hours. Cut into 1-inch pieces and store in an airtight container for up to a week.